The role of central oxytocin in obsessive compulsive disorder and related normal behavior.

Oxytocin (OT) is a neurosecretory nonapeptide synthesized in hypothalamic cells, which project to widely distributed sites in the CNS as well as the neurohypophysis. Central OT affects a variety of cognitive, grooming, affiliative, sexual, and reproductive behaviors in animals. Obsessive Compulsive Disorder (OCD) includes a range of cognitive and behavioral symptoms that bear some relationship to dimensions of behavior associated with OT. Anecdotal data and a recently completed cerebrospinal fluid (CSF) study provide evidence that some forms of OCD are related to OT dysfunction. Based on these findings, we hypothesize: 1) that some forms of OCD are at the extreme end of a range of normal behaviors that are mediated by OT and related systems; and that 2) some normal cognitive, affiliative, and sexual behaviors contain elements that are similar to features of OCD. Alternative hypotheses are considered, and a series of predictions are presented concerning the relationship between central OT and the onset, course, treatment response, and response to challenge procedures seen in this form of OCD.